Evernote is the one service available in Drafts that does not support multiple accounts.
Evernote’s integration story is a bit of a mess, frankly. I’ve tried to document some of that in the Evernote integration guide.
The direct integration only still works because I have forked their no-longer-supported integration SDK for iOS, does not work on Mac, and does not support some Evernote accounts (like ones which use Google for login) because of issues at Evernote’s end.
Hopefully they will migration to an industry standard REST API at some time in the future and integration can be on-par with other services, but until such a time, it’s pretty limited.